linux设备模型之input子系统

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摘要：

input子系统是kernel中比较简单的一个子系统，主要用来管理输入设备(触摸屏，键盘等等),个人感
觉可以作为driver的起点，输入设备不明思议，要提供输入信息，input子系统将这些信息当作事件，进行区分，实
时的上传！input中不是那么规矩，并没有抽象出来总线的概念(硬件上不存在)，而是用一个结构struct input_handle充当了总线

的结构，struct input_handle挂接了操作结构以及设备，input设备用struct input_dev结构来表示，操作函数用struct input_handler

来表示，注意这里input_handle和input_handler很相似，存在全局的input设备链表input_dev_list，用于连接所有input devices，

存在全局的input操作链表input_handler_list,用于挂接所有handler.

主要涉及目录：drivers/input

struct input_dev

一、相关数据结构

1.input device

   

struct input_dev {const char *name;               //名字const char *phys;               //物理地址const char *uniq;               //设备特殊标识码struct input_id id;             //设备idunsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)];  //设备属性相关位图unsigned long evbit[BITS_TO_LONGS(EV_CNT)];            //支持的事件unsigned long keybit[BITS_TO_LONGS(KEY_CNT)];          //key,button位图unsigned long relbit[BITS_TO_LONGS(REL_CNT)];          //相对坐标unsigned long absbit[BITS_TO_LONGS(ABS_CNT)];          //绝对坐标unsigned long mscbit[BITS_TO_LONGS(MSC_CNT)];          //杂项事件支持unsigned long ledbit[BITS_TO_LONGS(LED_CNT)];          //led相关unsigned long sndbit[BITS_TO_LONGS(SND_CNT)];          //音响效果相关unsigned long ffbit[BITS_TO_LONGS(FF_CNT)];unsigned long swbit[BITS_TO_LONGS(SW_CNT)];unsigned int hint_events_per_packet;unsigned int keycodemax;                              //键码表大小unsigned int keycodesize;                             void *keycode;                                        //按键扫描码int (*setkeycode)(struct input_dev *dev,              //老式扫描方法  const struct input_keymap_entry *ke,  unsigned int *old_keycode);int (*getkeycode)(struct input_dev *dev,  struct input_keymap_entry *ke);struct ff_device *ff;unsigned int repeat_key;struct timer_list timer;                             //定时器int rep[REP_CNT];struct input_mt_slot *mt;int mtsize;int slot;int trkid;struct input_absinfo *absinfo;unsigned long key[BITS_TO_LONGS(KEY_CNT)];unsigned long led[BITS_TO_LONGS(LED_CNT)];unsigned long snd[BITS_TO_LONGS(SND_CNT)];unsigned long sw[BITS_TO_LONGS(SW_CNT)];int (*open)(struct input_dev *dev);                 //open回调函数void (*close)(struct input_dev *dev);int (*flush)(struct input_dev *dev, struct file *file);int (*event)(struct input_dev *dev, unsigned int type, unsigned int code, int value);struct input_handle __rcu *grab;spinlock_t event_lock;struct mutex mutex;unsigned int users;bool going_away;bool sync;struct device dev;                                  //devices 模型struct list_headh_list;                    //连接相应的handlestruct list_headnode;                      //挂接到全局input_dev_list};

2.操作函数结构input_handler

struct input_handler {void *private;                            //私有属性结构void (*event)(struct input_handle *handle, unsigned int type, unsigned int code, int value);bool (*filter)(struct input_handle *handle, unsigned int type, unsigned int code, int value);bool (*match)(struct input_handler *handler, struct input_dev *dev);int (*connect)(struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id);void (*disconnect)(struct input_handle *handle);void (*start)(struct input_handle *handle);const struct file_operations *fops;int minor;const char *name;                          //名字const struct input_device_id *id_table;    //支持的devices,id表struct list_headh_list;   //用于连接到对应的handle的struct list_headnode;     //用于连接到全局的input_handler_list链表};

3.bus的充当者总体管理结构

struct input_handle {void *private;                     //私有数据结构int open;                          //open计数const char *name;                  //名字struct input_dev *dev;             //连接设备struct input_handler *handler;     //连接driver的操作函数struct list_headd_node;    //设备挂接点struct list_headh_node;    //handle挂接点};

二、相关的操作函数

1.关心一下核心文件input.c,input子系统的初始化:

static int __init input_init(void){int err;err = class_register(&input_class);                          //注册input类，出现在sys/class下       if (err) {pr_err("unable to register input_dev class\n");return err;}err = input_proc_init();                                    //在proc下添加相关信息(bus/input)if (err)goto fail1;err = register_chrdev(INPUT_MAJOR, "input", &input_fops);  //注册成字符设备，设备号13if (err) {pr_err("unable to register char major %d", INPUT_MAJOR);goto fail2;}return 0; fail2:input_proc_exit(); fail1:class_unregister(&input_class);return err;}

貌似戛然而止了，^.^!,
2.向input子系统添加设备的函数,

int input_register_device(struct input_dev *dev){static atomic_t input_no = ATOMIC_INIT(0);struct input_handler *handler;const char *path;int error;/* Every input device generates EV_SYN/SYN_REPORT events. */__set_bit(EV_SYN, dev->evbit);/* KEY_RESERVED is not supposed to be transmitted to userspace. */__clear_bit(KEY_RESERVED, dev->keybit);/* Make sure that bitmasks not mentioned in dev->evbit are clean. */input_cleanse_bitmasks(dev);if (!dev->hint_events_per_packet)dev->hint_events_per_packet =input_estimate_events_per_packet(dev);/* * If delay and period are pre-set by the driver, then autorepeating * is handled by the driver itself and we don't do it in input.c. */init_timer(&dev->timer);if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {dev->timer.data = (long) dev;dev->timer.function = input_repeat_key;dev->rep[REP_DELAY] = 250;dev->rep[REP_PERIOD] = 33;}if (!dev->getkeycode)dev->getkeycode = input_default_getkeycode;                //如果没有设置，设置成默认值if (!dev->setkeycode)dev->setkeycode = input_default_setkeycode;dev_set_name(&dev->dev, "input%ld",                               //name     (unsigned long) atomic_inc_return(&input_no) - 1);error = device_add(&dev->dev);                                   //标准设备的加入，这个，，加哪去了，没bus的野设备？？

if (error)                                                       //直接扔到系统全局总设备链表了return error;path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);pr_info("%s as %s\n",dev->name ? dev->name : "Unspecified device",path ? path : "N/A");kfree(path);error = mutex_lock_interruptible(&input_mutex);if (error) {device_del(&dev->dev);return error;}list_add_tail(&dev->node, &input_dev_list);                   //加入全局input device链表list_for_each_entry(handler, &input_handler_list, node)       //遍历handler链表，匹配合适的handlerinput_attach_handler(dev, handler);input_wakeup_procfs_readers();mutex_unlock(&input_mutex);return 0;}

继续跟一下input_attach_handler函数,

static int input_attach_handler(struct input_dev *dev, struct input_handler *handler){const struct input_device_id *id;int error;id = input_match_device(handler, dev);                                  //具体的匹配函数if (!id)return -ENODEV;error = handler->connect(handler, dev, id);                              //匹配后调用connect函数if (error && error != -ENODEV)pr_err("failed to attach handler %s to device %s, error: %d\n",       handler->name, kobject_name(&dev->dev.kobj), error);return error;}

还有个函数

static const struct input_device_id *input_match_device(struct input_handler *handler,struct input_dev *dev){const struct input_device_id *id;int i;for (id = handler->id_table; id->flags || id->driver_info; id++) {if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)if (id->bustype != dev->id.bustype)continue;if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR)if (id->vendor != dev->id.vendor)continue;if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT)if (id->product != dev->id.product)continue;if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION)if (id->version != dev->id.version)continue;MATCH_BIT(evbit,  EV_MAX);MATCH_BIT(keybit, KEY_MAX);MATCH_BIT(relbit, REL_MAX);MATCH_BIT(absbit, ABS_MAX);MATCH_BIT(mscbit, MSC_MAX);MATCH_BIT(ledbit, LED_MAX);MATCH_BIT(sndbit, SND_MAX);MATCH_BIT(ffbit,  FF_MAX);MATCH_BIT(swbit,  SW_MAX);if (!handler->match || handler->match(handler, dev))             //不光是调用match函数，上面的匹配也很严格，厂商return id;                                               //版本一个也不能少}return NULL;}

3.handler的注册

同样handler也要有注册的

int input_register_handler(struct input_handler *handler){struct input_dev *dev;int retval;retval = mutex_lock_interruptible(&input_mutex);if (retval)return retval;INIT_LIST_HEAD(&handler->h_list);if (handler->fops != NULL) {if (input_table[handler->minor >> 5]) {retval = -EBUSY;goto out;}input_table[handler->minor >> 5] = handler;}list_add_tail(&handler->node, &input_handler_list);         //加入全局handler链表list_for_each_entry(dev, &input_dev_list, node)            //遍历devices链表，匹配input_attach_handler(dev, handler);input_wakeup_procfs_readers(); out:mutex_unlock(&input_mutex);return retval;}

三、input deivce实例

这个东东还是找个例子看起来比较方便,

翻一翻touchscreen下s3c2410_ts.c,

直接进入主题看probe

static int __devinit s3c2410ts_probe(struct platform_device *pdev){struct s3c2410_ts_mach_info *info;struct device *dev = &pdev->dev;struct input_dev *input_dev;struct resource *res;int ret = -EINVAL;/* Initialise input stuff */memset(&ts, 0, sizeof(struct s3c2410ts));ts.dev = dev;info = pdev->dev.platform_data;if (!info) {dev_err(dev, "no platform data, cannot attach\n");return -EINVAL;}dev_dbg(dev, "initialising touchscreen\n");ts.clock = clk_get(dev, "adc");                                //申请clockif (IS_ERR(ts.clock)) {dev_err(dev, "cannot get adc clock source\n");return -ENOENT;}clk_enable(ts.clock);                                         //使能clockdev_dbg(dev, "got and enabled clocks\n");ts.irq_tc = ret = platform_get_irq(pdev, 0);                 //中断号if (ret < 0) {dev_err(dev, "no resource for interrupt\n");goto err_clk;}res = platform_get_resource(pdev, IORESOURCE_MEM, 0);       //相关寄存器地址if (!res) {dev_err(dev, "no resource for registers\n");ret = -ENOENT;goto err_clk;}ts.io = ioremap(res->start, resource_size(res));           //进行映射if (ts.io == NULL) {dev_err(dev, "cannot map registers\n");ret = -ENOMEM;goto err_clk;}/* inititalise the gpio */if (info->cfg_gpio)info->cfg_gpio(to_platform_device(ts.dev));       //相关gpio配置ts.client = s3c_adc_register(pdev, s3c24xx_ts_select,     //注意这里adc核心相关，select会启动timer上报adc事件     s3c24xx_ts_conversion, 1);if (IS_ERR(ts.client)) {dev_err(dev, "failed to register adc client\n");ret = PTR_ERR(ts.client);goto err_iomap;}/* Initialise registers */if ((info->delay & 0xffff) > 0)writel(info->delay & 0xffff, ts.io + S3C2410_ADCDLY);writel(WAIT4INT | INT_DOWN, ts.io + S3C2410_ADCTSC);input_dev = input_allocate_device();                    //这里重点，分配了一个input device设备if (!input_dev) {dev_err(dev, "Unable to allocate the input device !!\n");ret = -ENOMEM;goto err_iomap;}ts.input = input_dev;ts.input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);ts.input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);input_set_abs_params(ts.input, ABS_X, 0, 0x3FF, 0, 0);input_set_abs_params(ts.input, ABS_Y, 0, 0x3FF, 0, 0);ts.input->name = "S3C24XX TouchScreen";ts.input->id.bustype = BUS_HOST;ts.input->id.vendor = 0xDEAD;ts.input->id.product = 0xBEEF;ts.input->id.version = 0x0102;ts.shift = info->oversampling_shift;ts.features = platform_get_device_id(pdev)->driver_data;ret = request_irq(ts.irq_tc, stylus_irq, 0,          //申请中断，input设备大多都是使用中断的，pen down up事件  "s3c2410_ts_pen", ts.input);if (ret) {dev_err(dev, "cannot get TC interrupt\n");goto err_inputdev;}dev_info(dev, "driver attached, registering input device\n");/* All went ok, so register to the input system */ret = input_register_device(ts.input);             //这里注册input deviceif (ret < 0) {dev_err(dev, "failed to register input device\n");ret = -EIO;goto err_tcirq;}return 0; err_tcirq:free_irq(ts.irq_tc, ts.input); err_inputdev:input_free_device(ts.input); err_iomap:iounmap(ts.io); err_clk:del_timer_sync(&touch_timer);clk_put(ts.clock);return ret;}


看一下 input_allocate_device函数，
struct input_dev *input_allocate_device(void){struct input_dev *dev;dev = kzalloc(sizeof(struct input_dev), GFP_KERNEL);if (dev) {dev->dev.type = &input_dev_type;        //初始化成input类型dev->dev.class = &input_class; device_initialize(&dev->dev);mutex_init(&dev->mutex);spin_lock_init(&dev->event_lock);INIT_LIST_HEAD(&dev->h_list);INIT_LIST_HEAD(&dev->node);__module_get(THIS_MODULE);}return dev;}
irq用于判断pen down up，启动adc上报坐标事件.

未完待续....

Thanks






	
				
	
					   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
linux设备模型之input子系统
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	  	   
Linux设备模型之input子系统详解
	     		  
	  	   
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